Secretary of State Hillary Clinton remained in a New York hospital Monday. She was treated with anticoagulant medication after a blood clot was discovered. / Karen Bleier, AFP/Getty Images

by Liz Szabo, USA TODAY

by Liz Szabo, USA TODAY

The type of blood clot Secretary of State Hillary Rodham Clinton sustained is treatable with blood thinners, and once an appropriate dose is maintained, her doctors expect her to be released from the hospital and make a full recovery.

While any kind of blood clot in the head can be life threatening, doctors at New York-Presbyterian Hospital, where Clinton, 65, was admitted, say she did not suffer a stroke or neurological damage. They say they are confident the clot, related to her concussion, will dissolve. She was hospitalized Sunday.

Clinton "is making excellent progress and we are confident she will make a full recovery," the doctors said in the statement. "She is in good spirits, engaging with her doctors, her family, and her staff."

Her husband, Bill, and daughter, Chelsea, were spotted leaving the hospital after visiting. Chelsea tweeted: "Thank you to all for sending good thoughts my Mom's way. Grateful to all her doctors & that she'll make a full recovery!"

Clinton's clot is located in a vein in the space between the brain and the skull behind her right ear, according to a statement from her doctors, Lisa Bardack of Mount Kisco Medical Group in New York and Gigi El-Bayoumi of George Washington University in the District of Columbia.

She developed the concussion earlier in December after she fainted at home from dehydration brought about by a stomach bug she contracted during a trip to Europe. She has not been seen publicly since Dec. 7.

Doctors say they found the clot, called a right transverse sinus venous thrombosis, during a routine follow-up MRI, a scan of the brain.

These kinds of clots are potentially deadly because they can cause a stroke, hemorrhage or brain swelling, says Geoffrey Manley, chief of neurosurgery at San Francisco General Hospital.

Manley has no personal knowledge of Clinton's case, but he says this kind of clot forms in "a large draining vein behind the ear, that helps to drain the blood from the brain." Clots block off the outflow of blood from the brain.

The pressure of that blood can cause a leak in the vein, causing major bleeding in the skull, Manley says.

The clots can cause headaches, dizziness or changes in consciousness, says Keith Black, chairman of neurosurgery at Cedars-Sinai Medical Center in Los Angeles. The fact that the clot was found in a "routine" exam - rather than because it was causing symptoms - is a good sign, Black says.

It suggests that her brain had already found a way to divert blood flow through another vein. Clots that expand to block additional veins - leading to a buildup of blood - can be very dangerous.

"Mrs. Clinton is very lucky," Black says. "This could have been very serious if the clot ... had expanded."

Doctors have to be careful about administering blood thinners, which can cause bleeding. They typically perform an MRI first, to make sure there is no evidence of bleeding or blood pooling in the skull, says Neil Martin, chairman of neurosurgery at Ronald Reagan UCLA Medical Center in Los Angeles.

While these clots aren't common, they are a known complication of head injuries, so doctors watch for them, Manley says. They are more likely to develop if there is a fracture in that part of the skull. Doctors usually put patients with these clots in intensive care. After initial treatment with intravenous anticoagulants, which block clot formation, doctors usually switch to oral medications.

Inactivity, such as Clinton's recent bed rest, also can contribute to blood clots.

This isn't the first time the former first lady has suffered a blood clot. In 1998, Clinton was in New York fundraising for the midterm elections when a swollen right foot led her doctor to diagnose a clot in her knee requiring immediate treatment.

She had planned to step down as secretary of State at the beginning of President Obama's second term. Whether Clinton will return to work before she resigns remains a question. During her absence, she missed a congressional hearing on the deadly attack on the U.S. Consulate in Libya, and the announcement that Sen. John Kerry, D-Mass., would be nominated for her post.